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European Journal of Plant Pathology - The formal honeybush tea industry in South Africa is relatively new, and has tremendous growth potential. However, as with other cultivated crops, production...  相似文献   
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Barley/cereal yellow dwarf viruses (YDVs) cause yellow dwarf disease (YDD), which is a continuous risk to cereals production worldwide. These viruses cause leaf yellowing and stunting, resulting in yield reductions of up to 80%. YDVs have been a consistent but low‐level problem in European cereal cultivation for the last three decades, mostly due to the availability of several effective insecticides (largely pyrethroids and more recently neonicotinoids) against aphid vectors. However, this has changed recently, with many insecticides being lost, culminating in a recent European Union (EU) regulation prohibiting outdoor use of the neonicotinoid‐insecticide compounds. This change is coupled with the growing challenge of insecticide‐resistant aphids, the lack of genetic resources against YDVs, and a knowledge deficit around the parameters responsible for the emergence and spread of YDD. This means that economic sustainability of cereal cultivation in several European countries including France and United Kingdom is now again threatened by this aphid‐vectored viral disease. In this review, we summarize the current knowledge on the YDV pathosystem, describe management options against YDD, analyse the impacts of the neonicotinoid ban in Europe, and consider future strategies to control YDV. © 2020 Society of Chemical Industry  相似文献   
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Amoxicillin has become a major antimicrobial substance in pig medicine for the treatment and control of severe, systemic infections such as Streptococcus suis. The minimum inhibitory concentration 90% (MIC 90) is 0.06 μg amoxicillin/ml, and the proposed epidemiological cut‐off value (ECOFF) is 0.5 μg/ml, giving only 0.7% of isolates above the ECOFF or of reduced susceptibility. Clinical breakpoints have not been set for amoxicillin against porcine pathogens yet, hence the use of ECOFFs. It has also been successfully used for bacterial respiratory infections caused by Actinobacillus pleuropneumoniae and Pasteurella multocida. The ECOFF for amoxicillin against A. pleuropneumoniae is also 0.5 μg/ml demonstrating only a reduced susceptibility in 11.3% of isolates. Similarly, P. multocida had an ECOFF of 1.0 μg/ml and a reduced susceptibility in only 2.6% of isolates. This reduced susceptibility disappears when combined with the beta‐lactamase inhibitor, clavulanic acid, demonstrating that it is primarily associated with beta‐lactamase production. In contrast, amoxicillin is active against Escherichia coli and Salmonella species but using ECOFFs of 8.0 and 4.0 μg/ml, respectively, reduced susceptibility can be seen in 70.9% and 67.7% of isolates. These high levels of reduced susceptibility are primarily due to beta‐lactamase production also, and most of this resistance can be overcome by the combination of amoxicillin with clavulanic acid. Currently, amoxicillin alone is considered an extremely valuable antimicrobial in both human and animal medicine and remains in the critically important category of antibiotics alongside the fluoroquinolones and macrolides by the World Health Organization as well as the third‐ and fourth‐generation cephalosporins, but these cephalosporins show marked resistance to basic beta‐lactamase production and are only destroyed by the extended‐spectrum beta‐lactamases. Amoxicillin alone and in combination with clavulanic acid are currently classed together in Category 2 in the European Union. By reviewing the pharmacodynamic data and comparing this with pharmacokinetic data from healthy and infected animals and clinical trial data, it can be seen that the product has a good efficacy against S. suis and A. pleuropneumoniae, in spite of usage over many years. However, it may be much less efficacious on its own against E. coli, due to reduced susceptibility and resistance associated with beta‐lactamase production, which is largely overcome by the use of clavulanic acid. It is felt that this differentiation may be useful in future classification of amoxicillin alone, in comparison with its combined use with clavulanic acid and thereby preserve the use of the more critically important antibiotics in veterinary medicine and reducing the risk of their resistance being transmitted to human.  相似文献   
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Uromycladium acaciae is the cause of a severe wattle rust epidemic in plantations of Acacia mearnsii (black wattle) in southern Africa. Research on the biology of this damaging rust is assisting in the development of control strategies. One strategy under investigation is the identification and deployment of resistant lines of A. mearnsii. Selection of resistant families currently relies on large-scale, time-consuming and expensive field trials. In this study, we present a detailed artificial inoculation protocol for U. acaciae, which can be used to screen for resistance. The results of an experiment that used the protocol to screen the relative resistance of 12 families of A. mearnsii to U. acaciae are also presented. The developed artificial inoculation protocol can also be used to investigate several other aspects of this host–pathogen system.  相似文献   
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  1. Understanding population size and trend is critical information in species management and conservation. To enable accurate population trend estimates, consistent robust monitoring of a species is essential, particularly for a species such as the New Zealand (NZ) sea lion, Phocarctos hookeri , which has experienced an almost continuous decline in pup production since the late 1990s.
  2. This research examines the pup production estimates for all known breeding sites for this species, and using a stage‐structured matrix population model, estimates population size and trend between 1995 and 2015.
  3. Overall, it is estimated that 2,316 pups were born in 2015, a decrease of 13% since 1995 and a 27% decline since the highest pup production estimate in 1998. This decline has been driven by the significant decline of 48% at the main breeding area, the Auckland Islands since 1998.
  4. Using the stage‐structured matrix population model a total species population size of 11,767 sea lions (95% CrI: 10,790–12,923) was estimated. This is the lowest population size of any sea lion species. Trend data for the Auckland Islands indicated that pup and population numbers have decreased at 1.9% yr?1 in the last 20 yr, while total species population decline is 0.6% yr?1.
  5. Estimates of population trends for this species have been hindered by inconsistent monitoring at most breeding sites. This study strengthens the growing field of research highlighting the need for consistent long‐term monitoring for the conservation management of endangered species.
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